Waves in interplanetary shocks: a wind/WAVES study

We describe results from the first statistical study of waveform capture data during 67 interplanetary (IP) shocks with Mach numbers ranging from approximately 1-6. Most of the waveform captures and nearly 100% of the large amplitude waves were in the ramp region. Although solitary waves, Langmuir waves, and ion acoustic waves (IAWs) are all observed in the ramp region of the IP shocks, large amplitude IAWs dominate. The wave amplitude is correlated with the fast mode Mach number and with the shock strength. The observed waves produced anomalous resistivities from approximately 1-856 Omega.m (approximately 10(7) times greater than classical estimates.) The results are consistent with theory suggesting IAWs provide the primary dissipation for low Mach number shocks.     

The behaviour of the cosmic-ray equatorial anisotropy inside fast solar-wind streams ejected by coronal holes

Summary The cosmic-ray equatorial anisotropy inside broad high-speed solar-wind streams ejected by coronal holes,i.e. in quasi-stationary condition, is analysed over the years 1973–1974. From the beginning to the end of the stream the amplitudes of the first and second harmonics of the anisotropy are found to decrease remarkably by factors 2.5 and 2.0, respectively, while the phases do not show systematic variations. The development of the stream structure in the interplanetary space together with the Parker theory on the diurnal anisotropy in stationary condition give a plausible explaination for the large variation observed in the first harmonic of the anisotropy. The behaviour of the second harmonic is tentatively interpreted in the light of current theories. To speed up publication, the authors of this paper have agreed to not receive the proofs for correction.     

Direction of the anisotropy vector of TeV cosmic rays

The preliminary results of measuring the direction of the stellar anisotropy vector of cosmic rays with the Carpet array at the Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences) are presented. The direction of the anisotropy vector is determined by analyzing the distribution of time delays of the signal from distant detectors of the array with respect to its central part. It is shown that the anisotropy vector has the direction α₀ (R.A.) ≈ 1.5 h, δ₀ ≈ 62° in the equatorial coordinate system. At such a direction, the CR anisotropy measured with the Baksan Underground Scintillation Telescope and the Andyrchi array is ≈0.2%.     

Dynamics of vector spin glasses with random anisotropy

The dynamics of vector spin glasses with additional random anisotropy is investigated in the mean field approximation. We find a cross-over of the upper critical line from a behaviour of Heisenberg spins with a field-temperature dependence , for large fieldsH, to Ising like behaviourT _f –TT ^2/3 , for small fields and fixed anisotropy, in agreement with results of Kotliar and Sompolinsky. Here, andT _f are characteristic spin glass temperatures. In addition, one has a second line with reversed behaviour which presumably represents a cross-over line from weak to strong non-ergodicity. The local transverse susceptibility _T () varies for large fields and 0 along the upper critical line as ^vT , with a critical exponentV _T = 1/2 – 11D/60 J, whereD andJ are the anisotropy and exchange coupling constants, respectively. On the Ising-like part of the upper critical line one has isotropic spin glass parameters,q _L =q _T , and susceptibilities, and a critical exponent, which is similar to that of Ising spins along the de Almeida-Thouless line.Dedicated to B. Mühlschlegel on the occasion of his 60th birthdaySFB Aachen-Jülich-Köln     

Statistical anisotropy from vector curvaton in D-brane inflation

We investigate the possibility of embedding the vector curvaton paradigm in D-brane models of inflation in type IIB string theory in a simple toy model. The vector curvaton is identified with the U(1)$U(1)$ gauge field that lives on the world volume of a D3-brane, which may be stationary or undergoing general motion in the internal space. The dilaton is considered as a spectator field which modulates the evolution of the vector field. In this set-up, the vector curvaton is able to generate measurable statistical anisotropy in the spectrum and bispectrum of the curvature perturbation assuming that the dilaton evolves as e^−?∝a²$e^{-?}\propto a^2$ where a(t)$a(t)$ is the scale factor. Our work constitutes a first step towards exploring how such distinctive features may arise from the presence of several light fields that naturally appear in string theory models of cosmology.     

Observation by an air-shower array in Tibet of the multi-TeV cosmic-ray anisotropy due to terrestrial orbital motion around the Sun

We report on the solar diurnal variation of the galactic cosmic-ray intensity observed by the Tibet III air shower array during the period from 1999 to 2003. In the higher-energy event samples (12 and 6.2 TeV), the variations are fairly consistent with the Compton-Getting anisotropy due to the terrestrial orbital motion around the Sun, while the variation in the lower-energy event sample (4.0 TeV) is inconsistent with this anisotropy. This suggests an additional anisotropy superposed at the multi-TeV energies, e.g., the solar modulation effect. This is the highest-precision measurement of the Compton-Getting anisotropy ever made.     

Galactic cosmic-ray anisotropy and its modulation in the heliomagnetosphere, inferred from air shower observation at Mt. Norikura

Summary Extensive air showers (EAS) with median primary energy (E _m) of (10¹³÷10¹⁵) eV have been observed since 1970 at Mt. Norikura (2770 m above sea level; geographic latitude 36.1°N, longitude 137.6°E) in order to study a cosmic-ray sidereal daily variation of galactic origin. We report here a summary of the observed results. EAS shows a significant sidereal diurnal variation with an amplitude (0.060±0.003)% and a phase (0.8±0.3) h sidereal local time forE _m≈1.5·10¹³eV. Sidereal semi- and tridiurnal variations also are statistically significant. These variations are proved to be of galactic origin by a method which uses the difference of two directional (eastward and westward) air shower observations. It is found that these variations are subject, as predicted by Nagashimaet al., to the annual variation due to the heliomagnetospheric modulation of the galactic anisotropy, which dominates in the rigidity region ≈10¹²V, and further that the annual variation changes its phase due to the polarity reversal of the polar magnetic field of the Sun, which occurs at the period of the maximum solar activity. This indicates that the anisotropy is produced by the charged cosmic rays, contrary to the expectation from the γ-ray origin hypothesis suggested by Alexeenko and Navara. With the increase ofE _m, the anisotropy seems to be reduced as we have not been able to detect any significant sidereal variation in EAS withE _m≈2·10¹⁴eV. This seems contradictory to the conventional conclusion that the energy spectrum of the anisotropy is flat or slightly increases with energy.

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Riassunto Sono stati osservati sciami cosmici estensivi (EAS) con energia primaria mediana (E _m) di (10¹³⋎10¹⁵) eV dal 1970 a Mt. Norikura (2770m, latitudine geografica 36.1° N, longitudine 137.6° E) per studiare una variazione gionarliera siderale dei raggi cosmici di origine galattica. Si riporta una sintesi dei risultati osservati. EAS mostra una significativa variazione siderale diurna con ampiezza (0.060±0.03)% e fase (0.8±0.3)h in tempo locale siderale perE _m∼1.5·10¹³eV. Le variazioni siderali semi e tri-diurne sono risultate anch'esse statisticamente significative. Si prova che queste variazioni sono d'origine galattica con un metodo che utilizza la differenza tra due osservazioni di sciami cosmici direzionali (est e ovest). Si trova che queste variazioni sono soggette, come previsto da Nagashimaet al., alla variazione annuale dovuta alla modulazione eliomagnetica dell'anisotropia galattica, che domina nella regione di rigidità ∼10¹²V e inoltre che la variazione annuale cambia fase a causa dell'inversione di polarità del campo magnetico polare del Sole, chesi verifica nel periodo di massima attività solare. Ciò indica che l'anisotropia è prodotta da raggi cosmici carichi, contrariamente a quanto previsto dall'ipotesi sull'origine da raggi gamma, suggerita da Alexeenko e Navara. Con l'aumento diE _m, l'anisotropia sembra ridursi in quanto non siamo riusciti a rilevare una variazione siderale significativa in EAS conE _m∼2·10¹⁴ eV. Questo risultato sembra in contraddizione con la conclusione convenzionale che lo spettro di energia dell'anisotropia è piatto o cresce appena con l'energia.

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Резюме Широкие атмосферные ливни со средней первичной энергией (E _m), равной (10¹³⋎10¹⁵) зВ, наблюдались с 1970 года на г. Нарикура (2770 м над уровнем моря; географическая широта 36.1°N, долгота 137.6°E), с целяю исследовать суточное изменение сидерических космических лучей галактической природы. Предлагается обзор полученных результатов. Широкие атмосферные ливни обнаруживают значительное сидерическое суточное изменение с амплитудой (0.060±0.003)% и фазой 0.8±0.3 часа сидерического времени дляE _m∼1.5·10¹³ эВ. Сидерические полу-и трех-суточные изменения являются также статистически заметными. Доказывается, что эти изменения имеют галактическое происхождение. Этот результат получен с помощью метода, который использует разности при наблюдениях атмосферных ливней в двух направлениях (в восточном и западном направлениях). Получено, что эти вариации подчиняются, как было предсказано Нагашима и др., годовому изменению, обусловленному гелиомагнитосферной модуляцией галактической анизотропии, которая доминирует в области жесткости ∼10¹² D, и кроме того, годовая вариация изменяет фазу, в связи с реверсированием полярности магнитного поля Солнца, котороепроисходит в период максимума солнечной активности. Этот реультат показывает, что возникает анизотропия, вызванная заряженными космическими лучами, в противоположность рредсказанию Алексеенко и Навара, связанному с гипотезой происхождения γ-лучей. При увеличенииE _m анизотропия, повидимому, уменьшается, так как мы не смогли зарегистрировать какого-либо существенного сидерического изменения в пироких атмосферных ливнях в случаеE _m∼2·10¹⁴эВ. Это противоречит общепринятому заключению, что энергетический спектр анизотропии является пологим или слегка увеличивается с энергией.

     

Formulation of cosmic-ray solar daily variation and its seasonal variation, produced from generalized stationary anisotropy of solar origin

Summary In previous papers, we presented a formulation of the cosmic-ray solar daily variation and of its seasonal variation, produced from an axis-symmetric stationary anisotropy of solar origin. On the other hand, based on their theoretical study of cosmic-ray diffusionconvection in the solar system, Munakata and Nagashima have recently pointed out the existence of an axis-asymmetric anisotropy with respect to the IMF axis, which is not covered by the formulation. In order to include such a case, we extend, in this paper, the above formulation to a case of a generalized anisotropy, which is expressed by surface harmonics in the IMF polar-co-ordinate system.

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Riassunto In precedenti lavori abbiamo presentato una formulazione della variazione diurna solare dei raggi cosmici e della sua variazione stagionale, prodotta da un'anisotropia stazionaria assi-simmetrica di origine solare. D'altra parte, basandosi sui loro studi teorici della diffusione-convezione dei raggi cosmici nel sistema solare, Munakata e Nagashima hanno recentemente messo in evidenza l'esistenza di un'anisotropia assisimmetrica rispetto all'asse IMF che non è compresa nella formulazione. Per poter includere anche tale caso, abbiamo esteso, in questo lavoro, la suddetta formulazione al caso di un'anisotropia generalizzata che è espressa da armoniche di superficie nel sistema di coordinate polari IMF.

     

Energy spectrum of cosmic-ray muons

Summary The energy spectrum of cosmic-ray muons at sea-level is calculated by the numerical integration of a diffusion equation by assuming a scaling model. The calculated spectrum is in good agreement with the observed data of muons with the zenith angles of 0° and nearly 90°. Furthermore, by this comparison, it is concluded that the scaling model is valid up to the muon energy of 6.9 TeV. It is also found that the survival probability of muons at large zenith angles is in favour of that calculated by Ramana Murthy rather than that obtained by Dau, Carstensen and Jokisch. Two production spectra of muons obtained by Thompson and Whalley and Dauet al. are analysed in reference to the recent experimental data. As a result, it is concluded that the power law exponent of the differential-energy spectrum of muon parent particles is 2.75±0.15 in the muon energy range from 100 GeV to 6.9 TeV.

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Riassunto Si calcola lo spettro di energia dei muoni dei raggi cosmici per mezzo dell'integrazione numerica di un'equazione di diffusione assumendo un modello a scala variabile. Lo spettro calcolato è in buon accordo con i dati osservati dei muoni con angoli di zenith di 0° e quasi 90°. Inoltre da questo confronto si conclude che il modello a scala variabile è valido fino ad energie muoniche di 6.9 TeV. Si trova anche che la probabilità di sopravvivenza dei muoni ad angoli di zenith grandi è in favore di quella calcolata da Ramana Murthy piuttosto che di quella ottenuta da Dau, Cartensen e Jokisch. Si analizzano due spettri di produzione dei muoni ottenuti da Thomson e Whalley e Dauet al. rispetto a recenti dati sperimentali. Come risultato si conclude che l'esponente della legge di potenza dello spettro di energia differenziale delle particelle genitrici dei muoni è 2.75±0.15 nell'intervallo di energia muonica compreso tra 110 GeV e 6.9 TeV.

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Резюме Вычисляется энергетический спектр мюонов космических лучей на уровне моря, использия численное интегрирование уравнения диффузии и предполагая модель подобия. Вычисленный спектр хорошо согласуется с наблюденными данными для мюонов с зенитными углами вблизи 0° и 90°. Из этого сравнения делается вывод, что модель подобия справедлива для энергии мюонов вплоть до 6.9 ТэВ. Отмечается, что вероятность выживания мюонов при больших зенитных углах отдает предпочтение вычислениям Рамана Мурти, а не Дау, Карстенсена и Джокиша. Два спектра образования мюонов, полученные Томпсоном и Валлеем и Дау и др., сравниваются с недавними экспериментальными данными. Из сравнения получено, что показатель степенного закона в дифференциальном энергетическом спектре равен 2.75±0.15 в области энергий мюонов от 110 ГэВ до 6.9 ТэВ.

     

Fluctuations of cosmic rays and interplanetary magnetic field in the vicinity of interplanetary shock fronts

The spectral characteristic of fluctuations of cosmic rays (CRs) and the interplanetary magnetic field in the prefront region of interplanetary shock waves, where coherent CR fluctuations with energies from ～10 keV to ～1 GeV are often observed, have been studied. It is concluded that the spectrum of CR fluctuations is subjected to modulation by fast magnetosonic waves generated by low-energy CRs reflected and/or accelerated at the shock fronts.     

Energy spectrum of cosmic-ray neutrinos in the atmosphere

Summary The energy spectrum of cosmic-ray neutrinos in the atmosphere has been calculated for the neutrino energy from 0.2 GeV to 10⁸ GeV by taking into account the results of p-p collision, p-nucleus collision, nucleus-nucleus collision, the energy spectrum of primary cosmic rays, momentum spectrum and charge ratio of cosmic-ray muons measured by MUTRON, and the production of prompt neutrinos in the decay of charmed particles. Our result on neutrino intensity is in good agreement with the result of Osborneet al. for the horizontal direction if their muon spectrum has been corrected, and also with the result of Volkova for the vertical direction except for the lower energies. For the horizontal direction the intensity of prompt muon-neutrinos exceeds that of muonneutrinos from the conventional processes at the neutrino energy of 10⁶ GeV and also the intensity of prompt electron-neutrinos exceeds that of electron-neutrinos from the conventional processes at the energy of 10⁵ GeV. The corresponding values for the vertical direction are 10⁵ GeV and 10⁴ GeV, respectively. In the energy region from 0.3 GeV to 3 GeV, the expected value for the ratio of intensity of electron-neutrino to that of muon-neutrino is obtained as 0.42±0.08 and this is excellent agreement with the experimental value 0.36±0.13 of NUSEX group.

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Riassunto è stato calcolato lo spettro d’energia dei neutrini dei raggi cosmici nell’atmosfera per un’energia neutrinica da 0.2 a 10⁸ GeV tenendo conto dei risultati delle collisioni p-p, p-nucleo, nucleo-nucleo, dello spettro d’energia dei raggi cosmici primari, dello spettro dell’impulso e del rapporto di carica dei muoni dei raggi cosmici misurato da MUTRON e dalla produzione di neutrini pronti nel decadimento di particelle con charm. Il nostro risultato sull’intensità dei neutrini è in buon accordo con il risultato di Osborneet al. per la direzione orizzontale se il loro spettro muonico viene corretto, ed anche con il risultato di Volkova per la direzione verticale tranne che per le energie piú basse. Per la direzione orizzontale l’intensità dei neutrini muonici pronti è maggiore di quella dei neutrini muonici che derivano dai processi convenzionali ad energia neutrinica di 10⁶ GeV ed anche l’intensità dei neutrini elettronici pronti è maggiore di quella dei neutrini elettronici che derivano dai processi convenzionali all’energia di 10⁵ GeV. I valori corrispondenti per la direzione verticale sono rispettivamente 10⁵ e 10⁴ GeV. Nella regione d’energia tra 0.3 e 3 GeV, il valore atteso ottenuto per il rapporto tra l’intensità dei neutrini elettronici e quella dei neutrini muonici è 0.42±0.08 e questo è in accordo eccellente con il valore sperimentale 0.36±0.13 del gruppo NUSEX.

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Ёнергетический спектр нейтрино космических лучей в атмосфере

Резюме Вычисляется Энергетический спектр нейтрино космических лучей в атмосфере для Энергий нейтрино от 0.2 ГЭВ до 10⁸ ГЭВ, учитывая р-р соударения, р-ядерные соударения, ядерно-ядерные соударения, Энергетический спектр первичных космических лучей, импульсный спектр и зарядовое отнощение мюонов космических лучей, измеренных с помошью МUTRON, и образование нейтрино в распадах очарованных частиц. Нащ результат для интенсивности нейтрино хорощо согласуется с результатом Осборна и др. для горизонтального направления, если их мюонный спектр является правильным, а также с результатом Волковой для вертикального направления, за исключением низких Энергий. Для горизонтального направления интенсивность мгновенных мюонных нейтрино превыщает интенсивность мюон-ных нейтрино из обычных процессов при Энергиях нейтрино 10⁶ ГЭВ. Йнтенсивность мгновенных Электронных нейтрино превыщает интенсивность Электронных нейтрино из обычных процессов при Энергии 10⁵ ГЭВ. Соответствуюшие величины для вертикального направления соответственно равны 10⁵ ГЭВ и ДО⁴ ГЭВ. В области Энергий от 0.3 ГЭВ до 3 ГЭВ ожидаемая величина отнощения интенсивностей Электронных нейтрино к интенсивности мюонных нейтрино составляет 0.42±0.08. Ёта величина прекрасно согласуется с Экспериментальным результатом 0.36±0.13, полученным группой

     

16-month periodicity of cosmic-ray intensity

Summary Data from four neutron monitors, Climax (1953–1976), Deep River (1964–1977), Mt. Norikura (1957–1983) and Tokyo (1970–1983) are analysed. Power spectra reveal peaks at frequency 1c/16 months for all the stations. Harmonic analysis for the 16-month period is performed after eliminating the long-term solar-cycle variation. There is general agreement in the phases of the mean vectors for various neutron monitors. The amplitude averaged over all the four stations is 0.41±0.01, while it is higher for the two stations having lower cut-off rigidity as compared to that of the other two. The vectors are seen to become more consistent in phase for periods of minimum solar activity than those for maximum-activity period. The summation dials reveal abrupt changes in the directions of the 16-month wave vector corresponding to the reversal of polarity of the solar magnetic field. Comparison of the 16-month wave of sunspot activity with that of cosmic-ray intensity, however, does not show any significant correlation.

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Riassunto Si analizzano dati da quattro monitor di neutroni, Climax (1953–1976), Deep River (1964–1977), Mt. Norikura (1957–1983) e Tokyo (1970–1983). Gli spettri di frequenza rivelano picchi alla frequenza di 1 ciclo ogni 16 mesi per tutte le stazioni. Si effettua un'analisi armonica per un periodo di 16 mesi dopo aver eliminato la variazione del ciclo solare a lungo termine. Esiste un accordo generale riguardo alle fasi dei vettori medi per vari monitor di neutroni. L'ampiezza media rispetto a tutte e quattro le stazioni è di 0.41±0.01, mentre risulta superiore per le due stazioni che presentano una rigidità di taglio inferiore alle altre due. Si osserva una crescente coerenza di fase dei vettori in periodi di attività solare minima, rispetto a quella in periodi di attività massima. I grafici della somma rivelano cambiamenti repentini nelle direzioni del vettore d'onda di 16 mesi, corrispondenti all'inversione di polarità del campo magnetico del Sole. Il confronto di un'onda di 16 mesi dell'attività delle macchie solari con quella dell'intensità dei raggi cosmici, tuttavia, non mostra nessuna correlazione significativa.

     

Spectrographic investigations of the cosmic-ray events in December 2006

The Forbush decreases and ground-level enhancements in solar cosmic ray fluxes in December 2006 have been analyzed by the spectrographic method. The results showed a decrease in the cutoff rigidity and the spectrum power of variations during the main phase of Forbush decreases.     

Short-period variation of cosmic-ray intensity observed in the stratosphere

Summary To investigate the variation of the cosmic-ray intensity in the Earth atmosphere, stratospheric balloon soundings are performed weekly at Campinas (Brazil). During the flight of May 20th, 1988 short-period variations were detected. Through Fourier analysis it was identified a period of ∼2.5 min, with a confidence level of 99.6% between 23 g/cm² and 173 g/cm². Apparently these oscillations are not correlated either with the earth magnetic field or solar activity, suggesting their atmospheric origin, nevertheless it is difficult to explain the production mechanisms of these disturbances.

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Riassunto Per studiare le variazioni dell'intensità dei raggi cosmici nell'atmosfera terrestre sono messi in funzione palloni sonda stratosferici settimanalmente a Campinas (Brasile). Durante il volo del 20 Maggio 1988 sono state registrate variazioni a breve periodo. Mediante l'analisi di Fourier è stato identificato un periodo di ≈2.5 min con un livello di confidenza di 99.6% tra 23 g/cm² e 173 g/cm². Apparentemente queste oscillazioni non sono correlate né con il campo magnetico terrestre né con l'attività solare, il che suggerisce la loro origine atmosferica, nonostante sia difficile spiegare i meccanismi di produzione di queste perturbazioni.

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Резюме для исследования изменения интенсивности комсических лучей в земной атмосфере еженелельно запускайтся стратосферные шарызонды в лаборатории Кампинас (Бразилия). Во время подыта 20 мая 1988 года, были зарегистрированы изменения с коротким периодом. С помощью фурье-анализа определен период 2.5 минуты, с уровнем достоверности 99.6%, в области между 23 г/см² и 173 г/см². По-видимому, эти осцилляции не связаны ни с магнитным полем Земли, ни с солнечной активностью. Предполагается их атмосферное происхождение, тем не менее трудно обБяснить механизм образования этих возмущений.

     

High-energy hadrons and cosmic-ray muons in the atmosphere

Summary The experimental data on fluxes of high-energy hadrons and muons in the atmosphere are compared with the predictions based on the latest information about the properties of high-energy interactions and the primary cosmic-ray composition. It is demonstrated that the expected fluxes are in good agreement with the observations if protons dominate at energies up to 10¹⁵ eV.

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Riassunto Si confrontano i dati sperimentali sui flussi degli adroni e muoni ad alta energia nell'atmosfera con de previsioni basate sulle informazioni piú recenti sulle proprietà delle interazioni ad alta energia e la composizione primaria dei raggi cosmici. Si dimostra che i flussi attesi sono in buon accordo con le osservazioni se i protoni dominano ad energie fino a 10¹⁵ eV.

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Резюме Экспериментальные данные для потоков высокоэнергетических адронов и мюонов сравниваются с предсказаниями, основанными на последней информации относительно свойств взаимодействий при высоких энергиях и составе первичных космических лучей. Показывается, что ожидаемые потоки хорошо согласуются с наблюдениями, если протоны доминируют при энергиях вплоть до 10¹⁵ эВ.

     

The power spectrum analysis of the cosmic-ray diurnal variation

Summary We present a study of the CR diurnal variation by means of the power spectrum analysis of the neutron monitor flux as observed by a group of nonpolar stations. The power spectrum structure indicates a different behaviour for the two components—the steady and the transient—of the diurnal variation. The steady diurnal variation is found to be identical to the one obtained by averaging the diurnal vectors over a one-year period. Moreover, it appears to be made up of two parts, the first one apparently constant over a period of at least 8 years and the second one whose amplitude and phase appear randomly variable over a period comparable to a fraction of a year. The transient diurnal variation instead is correlated to the fluctuations of the interplanetary magnetic field and it is in agreement with the scintillation model of Jokipii and Owens.

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Riassunto Si è studiata la variazione diurna dei RC mediante l'analisi della sua densità spettrale di potenza. I dati usati sono quelli di un gruppo di stazioni non polari per il conteggio dei neutroni. Si è trovato un comportamento della variazione diurna stazionaria differente da quello della transitoria. La variazione stazionaria risulta identica a quella calcolabile col metodo della media della variazione diurna su periodi comparabili con l'anno. Inoltre essa risulta costituita da una parte apparentemente costante su almeno otto anni e di una componente con fase ed ampiezza variabili a caso su periodo comparabile con una frazione di anno. La variazione transitoria appare invece correlata con le fluttuazioni del campo magnetico interplanetario ed in buon accordo col modello delle scintillazioni di Jokipii e Owens.

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Резюме Мы исследуем дневное изменение спектра космических лучей, анализируя данные с нейтронных мониторов группы неполярных стаций. Структура степенного спектра указывает на различное поведение двух компонет—стационарной и переходной—дневного изменения. Обнаружено, что стационарное дневное изменение идентично изменению, полученному в результате усреднения данных за годичный период. Более того, стационарное дневное изменение состоит из двух частей. Первая часть является постоянной за период, по крайней мере, 8 лет. Вторая часть дневного изменения имеет амплитуду и фазу, которые меняются случайным образом в течение периода, сравнимого с частью года. Переходное дневное изменение коррелирует с флуктуациями межпланетного магнитного поля и согласуется с сцинтилляционной моделью Джокипия и Овенса.

     

Silicon fragmentation under the effect of high-energy cosmic-ray protons

The results obtained by calculating the cross sections for the elastic and inelastic scattering of 50- to 1000-MeV protons interacting with ²⁸Si, which is the main integrated-circuit element of onboard spacecraft electronics, are presented along with the calculated mass, charge, and energy distributions of heavy products of respective nuclear reactions. To compare the results of the calculations with experimental data, similar calculations were performed for the p + ²⁷Al reaction. This comparison shows that the elasticand inelastic-scattering cross sections calculated by using the EMPIRE-II-19 code are in satisfactory agreement with available experimental data. Considerably wider scatter of available data is observed in the isotope and isobar yields. A high sensitivity of the kinetic spectrum of the final nuclei to the incident-proton energy is demonstrated.